"Clients are inundating us with messages of support, and placing new business with us, showing how much they want us to succeed," he wrote. "Over the weekend our partners in other divisions have confirmed that they cannot achieve their ambitious goals without a healthy and vibrant investment bank alongside, co-operating at every level."

He also said that they needed to "move forward forcefully and decisively." Another UBS executive called the trade "a terrorist attack" that was unforeseeable and unavoidable.